Investigation on the structure and properties of different PE blown films

Molecular orientation and structure development during film blowing have a major effect on mechanical and physical properties of polyethylene films. In this work the structures and morphology of three different polyethylene blown films; linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high density polyethylene (HDPE) were studied. A series of blown films were produced at different process conditions. The orientation of lamellae and lamellar stacks and the morphology of the films were characterized by SEM, AFM and X-ray diffraction. SEM images of the film plane surface MT (Machine-Transverse) and cross section slices in TN (Transverse-Normal) and MN (Machine-Normal) planes were made and compared with AFM images. It was observed that the surface morphology reflects a continuation of the bulk morphology for the cases studied. Changes in the blown film process parameters, such as take up ratio (TUR), blow up ratio (BUR) and frost line height (FLH) have an effect on structural parameters, crystallinity and mechanical properties.